Implement Ruby version faker.

During cross compilation, rake-compiler will create a fake.rb
file to mimic a different version than the one used to execute
the build process.

Yet still, there are some changes between 1.9 and 1.8 not yet
ironed.

2 files changed, 57 insertions, 12 deletions

diff --git a/lib/rake/extensiontask.rb b/lib/rake/extensiontask.rb
index e81595a..522ad2f 100644
--- a/lib/rake/extensiontask.rb
+++ b/lib/rake/extensiontask.rb
@@ -102,17 +102,30 @@ module Rake
       file "#{tmp_path}/Makefile" => [tmp_path, extconf] do |t|
         options = @config_options.dup
 
+        # include current directory
+        cmd = ['-I.']
+
+        # if fake.rb is present, add to the command line
+        if t.prerequisites.include?("#{tmp_path}/fake.rb") then
+          cmd << '-rfake'
+        end
+
+        # now add the extconf script
+        cmd << File.join(Dir.pwd, extconf)
+
         # rbconfig.rb will be present if we are cross compiling
         if t.prerequisites.include?("#{tmp_path}/rbconfig.rb") then
           options.push(*@cross_config_options)
         end
 
-        parent = Dir.pwd
+        # add options to command
+        cmd.push(*options)
+
         chdir tmp_path do
           # FIXME: Rake is broken for multiple arguments system() calls.
           # Add current directory to the search path of Ruby
           # Also, include additional parameters supplied.
-          ruby ['-I.', File.join(parent, extconf), *options].join(' ')
+          ruby cmd.join(' ')
         end
       end
 
@@ -222,14 +235,21 @@ module Rake
       # define compilation tasks for cross platfrom!
       define_compile_tasks(cross_platform)
 
-      # chain rbconfig.rb to Makefile generation
-      file "#{tmp_path}/Makefile" => ["#{tmp_path}/rbconfig.rb"]
+      # chain fake.rb and rbconfig.rb to Makefile generation
+      file "#{tmp_path}/Makefile" => ["#{tmp_path}/fake.rb", "#{tmp_path}/rbconfig.rb"]
 
       # copy the file from the cross-ruby location
       file "#{tmp_path}/rbconfig.rb" => [rbconfig_file] do |t|
         cp t.prerequisites.first, t.name
       end
 
+      # genearte fake.rb for different ruby versions
+      file "#{tmp_path}/fake.rb" do |t|
+        File.open(t.name, 'w') do |f|
+          f.write fake_rb(ruby_ver)
+        end
+      end
+
       # now define native tasks for cross compiled files
       define_native_tasks(cross_platform) if @gem_spec && @gem_spec.platform == 'ruby'
 
@@ -279,5 +299,16 @@ module Rake
     def source_files
      @source_files ||= FileList["#{@ext_dir}/#{@source_pattern}"]
     end
+
+    def fake_rb(version)
+      <<-FAKE_RB
+        class Object
+          remove_const :RUBY_PLATFORM
+          remove_const :RUBY_VERSION
+          RUBY_PLATFORM = "i386-mingw32"
+          RUBY_VERSION = "#{version}"
+        end
+FAKE_RB
+    end
   end
 end
diff --git a/spec/lib/rake/extensiontask_spec.rb b/spec/lib/rake/extensiontask_spec.rb
index e0d7eae..eb385b6 100644
--- a/spec/lib/rake/extensiontask_spec.rb
+++ b/spec/lib/rake/extensiontask_spec.rb
@@ -261,6 +261,8 @@ describe Rake::ExtensionTask do
         @config_file = File.expand_path("~/.rake-compiler/config.yml")
         @ruby_ver = RUBY_VERSION
         @config_path = mock_config_yml["rbconfig-#{@ruby_ver}"]
+
+        File.stub!(:open).and_yield(mock_fake_rb)
       end
 
       it 'should not generate an error if no rake-compiler configuration exist' do
@@ -294,16 +296,17 @@ describe Rake::ExtensionTask do
         config = mock(Hash)
         config.should_receive(:[]).with("rbconfig-1.9.1").and_return('/path/to/ruby/1.9.1/rbconfig.rb')
         YAML.stub!(:load_file).and_return(config)
-        begin
-          ENV['RUBY_CC_VERSION'] = '1.9.1'
-          Rake::ExtensionTask.new('extension_one') do |ext|
-            ext.cross_compile = true
-          end
-        ensure
-          ENV.delete('RUBY_CC_VERSION')
+
+        ENV['RUBY_CC_VERSION'] = '1.9.1'
+        Rake::ExtensionTask.new('extension_one') do |ext|
+          ext.cross_compile = true
         end
       end
 
+      after :each do
+        ENV.delete('RUBY_CC_VERSION')
+      end
+
       describe "(cross for 'universal-unknown' platform)" do
         before :each do
           @ext = Rake::ExtensionTask.new('extension_one', @spec) do |ext|
@@ -312,6 +315,12 @@ describe Rake::ExtensionTask do
           end
         end
 
+        describe 'fake' do
+          it 'should chain fake task to Makefile generation' do
+            Rake::Task['tmp/universal-unknown/extension_one/Makefile'].prerequisites.should include('tmp/universal-unknown/extension_one/fake.rb')
+          end
+        end
+
         describe 'rbconfig' do
           it 'should chain rbconfig tasks to Makefile generation' do
             Rake::Task['tmp/universal-unknown/extension_one/Makefile'].prerequisites.should include('tmp/universal-unknown/extension_one/rbconfig.rb')
@@ -359,7 +368,12 @@ describe Rake::ExtensionTask do
   def mock_config_yml
     {
       'rbconfig-1.8.6' => '/some/path/version/1.8/to/rbconfig.rb',
-      'rbconfig-1.9.1' => '/some/path/version/1.9.1/to/rbconfig.rb'
+      'rbconfig-1.9.1' => '/some/path/version/1.9.1/to/rbconfig.rb',
+      'rbconfig-3.0.0' => '/some/fake/version/3.0.0/to/rbconfig.rb'
     }
   end
+
+  def mock_fake_rb
+    mock(File, :write => 45)
+  end
 end